Article having composite hard coat layer and method for forming composite hard coat layer

ABSTRACT

The present invention provides inexpensively an article with a hard coat excellent in anti-staining property, lubricity, scratch resistance and abrasion resistance. The present invention provides a method for forming the hard coat. A hard coat agent composition comprising an active energy ray-curable compound is applied onto a surface of an article  1  to be hard-coat-treated, thereby forming a hard coat agent composition layer, a surface material layer is formed by film-forming with a surface layer material comprising an active energy ray-curable compound having anti-staining property and/or lubricating property on the surface of the hard coat agent composition layer, and active energy rays are irradiated onto the formed hard coat agent composition layer and surface material layer so as to cure the two layers simultaneously, thereby forming a hard coat layer  2  contacting the surface of the article  1  and an anti-staining surface layer  3  contacting the surface of the hard coat layer  2.

TECHNICAL FIELD

The present invention relates to an article with a composite hard coatlayer and a method for forming a composite hard coat layer. In thepresent invention, a composite hard coat layer includes a hard coatlayer which is formed on a surface of an article and has scratchresistance and abrasion resistance, and an anti-staining surface layerwhich is formed on the surface of the hard coat layer and hasanti-staining property and lubricity. More specifically, the presentinvention relates to an article having, on a surface thereof, acomposite hard coat layer having anti-staining property, lubricity,scratch resistance and abrasion resistance in the field of variousarticles for which these properties are required, and a method forforming the composite hard coat layer.

In particular, the present invention concerns a method for forming acomposite hard coat layer having anti-staining property, lubricity,scratch resistance and abrasion resistance on a surface of an opticalrecording medium, a magneto-optical recording medium, an optical lens,an optical filter, an anti-reflection film, or any one of variousdisplay elements such as a liquid crystal display, a CRT display, aplasma display and an EL display, without deteriorating these opticalproperty and recording property, and also concerns an article on whichthis hard coat layer is formed.

BACKGROUND ART

Usually, a protective layer (hard coat layer) is given to the surface ofvarious articles for which scratch resistance and abrasion resistanceare required, for example, optical recording media such as a CD (CompactDisk) and a DVD (Digital Versatile Disk), magneto-optical recordingmedia, an optical lens, an optical filter, an anti-reflection film, andvarious display elements such as a liquid crystal display, a CRTdisplay, a plasma display and an EL display.

In many cases, stains such as a fingerprint, sebum, sweat and cosmeticsare adhered to the surface of these articles by user's use of thearticles. Once such stains are adheres thereto, they are not easilyremoved. This is a serious problem, in particular, for optical recordingmedia or optical lenses used to record or reproduce the media since therecording and reproducing of information signals are remarkablyobstructed by the adhered stains.

In magneto-optical recording media, a magnetic head runs on an organicprotective layer formed on their recording layer. Accordingly, it isrequired that the abrasion resistance of the protective layer is madehigh and, simultaneously, the frictional coefficient thereof is madelow.

As the method for solving the former problem, suggested are variousmethods of forming, on the surface of an optical lens or the like, alayer having a nature that stains do not adhere easily to the layer andeven if stains adhere to the layer, the stains are easily wiped off,that is, a layer having anti-staining property. Specifically, thefollowing method is adopted in many cases: a method of forming a layermade of a fluorine-containing compound or a silicone-based compound onthe surface to give water repellency and oil repellency to the surface,thereby improving the anti-staining property.

About the method for overcoming the latter problem, that is, the methodfor decreasing the frictional coefficient of the surface of a protectivelayer (hard coat layer), many measures have been suggested so far.Specifically, the following method is used in many cases: a method offorming, on the surface of the protective layer, a film made of a liquidlubricant such as a fluorine-containing polymer (for example,perfluoropolyether) or a silicone polymer (for example,polydimethylsiloxane), thereby improving lubricity.

Originally, the former anti-staining property and the latter lubricityare entirely different properties. However, it is common to the two thata fluorine-containing compound or a silicone compound is used as meansfor giving each of these properties in many cases. Accordingly, problemscommon to the two are frequently caused when a fluorine-containingcompound or a silicone compound is used to give anti-staining propertyor lubricity to the surface of a hard coat.

Many fluorine-containing compounds or silicone compounds are soft. Thus,when these compounds are used, it is very difficult to obtain asufficient abrasion resistance. In order to overcome such a problem, thefollowing method can be considered: a method of adding an inorganicfiller made of SiO₂ fine particles or the like to a fluorine-containingpolymer or silicone polymer matrix to make the abrasion resistance high.According to such a method, however, a little improvement is made but asatisfactory abrasion resistance cannot be obtained as far as thefluorine-containing polymer or silicone polymer is used as the matrix,wherein the inorganic filler is dispersed.

Therefore, the following method is considered: a method of making aprotective layer into a lamination structure composed of two or moredifferent layers, making the lower layer into a layer made of a highlyhard material, and forming an upper layer made of a fluorine-containingcompound or silicone compound on the surface thereof, thereby givinganti-staining property or lubricity. In this case, it is preferable tomake the upper layer, which is made of the fluorine-containing compoundor silicone compound, as thin as possible so as to reflect the hardnessof the lower layer in the upper layer, which constitutes the topmostsurface of the lamination protective layer. However, in this method, itis very difficult to obtain close adhesion between the lower layer andthe upper layer which is made of the fluorine-containing compound orsilicone compound.

As the method for solving the above-mentioned problem about theadhesion, for example, the following method is known: a method offorming a lower layer made of an inorganic material such as SiO₂ by sucha process as sputtering or sol-gel process; forming, on the surface ofthe lower layer, an upper layer made of alkoxysilane having afluoroalkyl group by such a process as vapor deposition or solutionapplication; subjecting the resultant to heat treatment in the presenceof a very small amount of water content so as to cause dehydrationcondensation between silanol groups generated by hydrolysis of thealkoxysilane and/or between the silanol groups and hydroxyl groupspresent in the surface of the lower layer made of SiO₂ or the like,whereby the upper layer is fixed onto the lower layer surface throughchemical bonds and/or hydrogen bonds.

In this method, it is desired that the lower layer surface has activegroups such as hydroxyl groups at a high density. Therefore, thematerial that can be used in the lower layer is limited to an inorganicmaterial, in particular, a metal oxide or a metal chalcogenide such asSiO₂, Al₂O₃, TiO₂ or ZnS. Even when the lower layer is made of a metaloxide such as SiO₂, in order to make adhesion between this metal oxideand the alkoxysilane of the upper layer sufficient, it is necessary tosubject the lower layer surface to activating treatment, such as alkalitreatment, plasma treatment or corona discharge treatment, forincreasing the density of active groups on the surface before theformation of the upper layer.

An attempt is also made for using a lower layer made of an organicmaterial such as polyethylene, polycarbonate or polymethyl methacrylate;making the surface of the lower layer hydrophilic by such a method asplasma treatment or corona discharge treatment; and forming an upperlayer made of the same alkoxysilane as described above on the surface ofthe lower layer. In this case, however, the adhesion is far poorer thanin the case that the above-mentioned inorganic material is used as thelower layer. Thus, a sufficient endurance is not obtained.

In the case that a substrate to be hard-coat-treated is made of resin,according to the above-mentioned method in which an inorganic materialsuch as SiO₂ is used as the lower layer, it is very difficult to obtainthe abrasion resistance of the hard coat. When the layer made of theinorganic material such as SiO₂ is deposited on the surface of the resinsubstrate, the thickness of the film which can be formed is at mostabout several hundred nanometers. It is difficult from the standpoint ofthe production process thereof to make the film thickness larger thansuch a value. Even if such a film can be formed, the inorganic filmself-breaks easily since a difference in elastic modulus or thermalexpansion coefficient between the inorganic film and the substrate isremarkably large. It is however difficult that the inorganic film havinga thickness of several hundred nanometers gives a sufficient abrasionresistance. It is also difficult to obtain a sufficient adhesion betweenthe resin substrate and the inorganic film. Consequently, the inorganicfilm is easily peeled. From this viewpoint, it is difficult to obtain asufficient abrasion resistance, as well.

Therefore, in the case that the substrate to be hard-coat-treated ismade of resin, it is necessary to form a primer layer having a highelastic modulus on the resin substrate, form a lower layer made of thesame inorganic film as described above on the primer layer, therebykeeping the adhesion between the resin substrate and the inorganic filmand the strength of the inorganic film, subject the surface of the lowerlayer to activating treatment, and form an upper layer made of the samefluorine-containing alkoxysilane as described above on the lower layersurface. Since it is necessary to form the three layers successively inthis way, the productivity is very poor.

Japanese Laid-open Patent Publication No. 9-137117(1997) discloses amethod of applying, onto a surface of a resin substrate, a compositioncomprising a polymerizable compound having in the molecule thereof atleast two (meth)acryloyloxy groups and inorganic compound fine particlessuch as silica fine particles; photo-polymerizing and curing thepolymerizable compound by irradiation of active energy rays; subjectingthe surface of this cured film to corona treatment or plasma treatment;and then applying, onto the treated surface, a silane compound having inthe molecule thereof at least one group which can generate a silanolgroup by hydrolysis, thereby forming a silane compound coat having animproved adhesion to the above-mentioned cured film. In this case, inorder to keep the adhesion between the silane compound coat as the upperlayer and the cured film as the lower layer, it is likewise necessary tosubject the cured film surface to corona treatment or plasma treatment.

In the case that about an organic protective layer of theabove-mentioned magneto-optical recording medium a liquid lubricant suchas perfluoropolyether or polydimethylsiloxane is applied onto thesurface of the organic protective layer to form a lubricant film, theadhesion between the organic protective layer and the liquid lubricantfilm may not be considered very much since the lubricant is a viscousliquid. However, there is a possibility in that the lubricant isdecreased by sliding a magnetic field modulating head repeatedly for along term or the lubricant volatizes little by little in storage of therecording medium over a long term. In this method, therefore, it isdesirable that the lubricant is firmly fixed on the organic protectivelayer surface.

Meanwhile, in order to obtain anti-staining property, it is necessary togive water repellency or oil repellency to the surface of a protectivelayer, as described above. However, this manner is not necessarilysufficient. The operation of wiping off adhering stains is generallycarried out by users. Therefore, in order that users can feel that theoperation of wiping off stains is easy at the time of carrying out thisoperation, it is necessary to decrease the frictional coefficient of theprotective layer surface. Relationship between the anti-stainingproperty of an article and the frictional coefficient thereof has hardlybeen pointed out so far. In reality, however, in order to giveanti-staining property, it is essential to make the frictionalcoefficient low as well as give water repellency and oil repellency.

By making the frictional coefficient of the surface low, an impactcaused when a hard projection contacts the surface can be slipped away;therefore, the generation of scratches can be suppressed. Accordingly,from the standpoint of improving the scratch resistance of the hardcoat, it is required to make the frictional coefficient of the surfacelow, as well.

Japanese Laid-open Patent Publication Nos. 6-211945 (1994) and2000-301053 disclose the formation of a hard coat layer by: applying,onto a substrate, a composition wherein fluoroalkyl acrylate and anacrylic monomer incompatible with this are dissolved at a given ratio ina solvent capable of dissolving the two; and irradiating electron raysonto the composition immediately after the application so as to cure thecomposition. According to these publications, by the application of thecomposition into a thickness of 1 to 15 μm and the irradiation of theelectron rays immediately after the application, the solvent isinstantaneously vaporized. Additionally, the fluoroalkyl acrylatecompound and the acrylic monomer are localized so that the compositionis cured in the state that the fluoroalkyl acrylate is distributedunevenly in the surface of the coat.

However, according to the two publications, it is necessary to irradiatethe electron rays onto the composition so as to cure the compositioninstantaneously after the application of the composition and before theuneven distribution based on the volatilization of the solvent becausethe composition containing the components incompatible with each otheris used. Accordingly, the timing of irradiating the electron rays afterthe application is difficult and the method for the application isrestricted very much. Coating methods in which the evaporation rate ofthe solvent is large, for example, spin coating cannot be used.

A most serious problem in the methods disclosed in the publications isthat there is a high possibility in that since the solvent is vaporizedat the same time when the electron rays are irradiated, the solvent inthe cured coat cannot be completely removed. In the publications, it isnot at all examined whether the solvent is completely removed from thecured coat or not. In the case that a very small amount of the solventremains inside, no problem is caused immediately after the formation ofthe hard coat but there is a possibility in that the coat is cracked orpeeled after the use of the article with the coat over a long term. Thehardness also becomes insufficient. Thus, a warp of the substrate onwhich the hard coat is formed is apt to increase gradually.

In the method of vaporizing the solvent at the same time when theelectron rays are irradiated, the cured coat is apt to have a porousstructure. Thus, the hardness thereof is insufficient and, further, theoptical property may deteriorate. Accordingly, even if no problem iscaused in the case of applying this method to the production of familiararticles, it is difficult to apply the method to the production ofarticles for which a very high optical property is required, forexample, an optical lens or an optical recording medium.

In short, a hard coat wherein anti-staining property, lubricity andabrasion resistance are simultaneously realized at high levels has neverbeen known so far.

DISCLOSURE OF THE INVENTION OBJECTS OF THE INVENTION

An object of the present invention is to solve the above-mentionedproblems in the background art and to provide inexpensively an articlewith a hard coat excellent in anti-staining property, lubricity, scratchresistance and abrasion resistance. Still another object of the presentinvention is to provide a method for forming a hard coat excellent inanti-staining property, lubricity, scratch resistance and abrasionresistance inexpensively and easily.

SUMMARY OF THE INVENTION

The present inventors made eager investigation. As a result, the presentinventors have found out that a hard coat layer having scratchresistance and abrasion resistance is cured/made on a surface of anarticle, and an anti-staining surface layer having anti-stainingproperty and lubricity is cured/made on the surface of the hard coatlayer simultaneously by irradiating active energy rays onto the twolayers, thereby forming a composite hard coat layer in which theanti-staining surface layer and the hard coat layer are firmly adheredto each other. Thus, the present invention has been made.

A first aspect of the present invention is an article with a compositehard coat layer comprising a hard coat layer on the surface of thearticle and an anti-staining surface layer on the surface of the hardcoat layer, wherein the hard coat layer is made of a cured product of ahard coat agent composition comprising an active energy ray-curablecompound, the anti-staining surface layer is made of a cured product ofa surface layer material comprising an active energy ray-curablecompound having anti-staining property and/or lubricating property, andthe anti-staining surface layer is fixed on the hard coat layer. Thewords “is fixed” means that about the water repellency of the compositehard coat layer as described in Examples, the contact angle of water onthe hard coat surface is 85 degrees or more at both of the initial timeand the time after a cloth is slid on the surface. If the hard coatlayer is not fixed, the contact angle of 85 degrees or more cannot beattained, in particular, after the sliding.

It is preferable in the first aspect of the present invention that theanti-staining surface layer has a thickness of 1 nm or more and 100 nmor less.

It is preferable in the first aspect of the present invention that theactive energy ray-curable compound comprised in the hard coat agentcomposition is a compound having at least one reactive group selectedfrom the group consisting of a (meth)acryloyl group, a vinyl group and amercapto group.

It is preferable in the first aspect of the present invention that theactive energy ray-curable compound comprised in the surface layermaterial is a compound having at least one reactive group selected fromthe group consisting of a (meth)acryloyl group, a vinyl group and amercapto group.

It is preferable in the first aspect of the present invention that theactive energy ray-curable compound comprised in the surface layermaterial comprises a compound having a moiety having silicone-basedand/or fluorine-containing substituent, and having at least one reactivegroup selected from the group consisting of a (meth)acryloyl group, avinyl group and a mercapto group.

It is preferable in the first aspect of the present invention that thehard coat agent composition comprises a photopolymerization initiator,and comprises an inorganic filler if necessary.

A second aspect of the present invention is a method for forming acomposite hard coat layer comprising a hard coat layer and ananti-staining surface layer on a surface of an article, the methodcharacterized in the steps of

-   -   applying a hard coat agent composition comprising an active        energy ray-curable compound onto a surface of an article to be        hard-coat-treated, thereby forming a hard coat agent composition        layer,    -   film-forming, on the surface of the hard coat agent composition        layer, with a surface layer material comprising an active energy        ray-curable compound having anti-staining property and/or        lubricating property, thereby forming a surface material layer,        and    -   irradiating active energy rays onto the formed hard coat agent        composition layer and surface material layer so as to cure the        two layers simultaneously, thereby forming a hard coat layer        contacting the surface of the article and an anti-staining        surface layer contacting the surface of the hard coat layer.

It is preferable in the second aspect of the present invention that theanti-staining surface layer is formed to have a thickness of 1 nm ormore and 100 nm or less.

It is preferable in the second aspect of the present invention thatafter the hard coat agent composition is applied onto the surface of thearticle, thereby forming the hard coat agent composition layer, the hardcoat agent composition layer is dried to remove a solvent contained inthe hard coat agent composition from the hard coat agent compositionlayer, and then the surface material layer is formed on the surface ofthe hard coat agent composition layer.

It is preferable in the second aspect of the present invention thatafter the hard coat agent composition is applied onto the surface of thearticle, thereby forming the hard coat agent composition layer, the hardcoat agent composition layer is dried if necessary, active energy raysare irradiated onto the hard coat agent composition layer to turn thiscomposition layer into a half-cured state, and then the surface materiallayer is formed on the surface of the hard coat agent composition layer.

It is preferable in the second aspect of the present invention that thesurface material layer is formed by film-forming with the surface layermaterial by applying or depositing.

It is preferable in the second aspect of the present invention that atthe time of film-forming by applying the surface layer material, thereis used, as a solvent, a solvent in which the active energy ray-curablecompound in the already-formed hard coat agent composition layer is notsubstantially dissolved. In the case that the surface material layer isformed by applying the surface layer material, the surface materiallayer is dried after the applying.

It is preferable in the second aspect of the present invention that theactive energy ray-curable compound comprised in the hard coat agentcomposition is a compound having at least one reactive group selectedfrom the group consisting of a (meth)acryloyl group, a vinyl group and amercapto group.

It is preferable in the second aspect of the present invention that theactive energy ray-curable compound comprised in the surface layermaterial is a compound having at least one reactive group selected fromthe group consisting of a (meth)acryloyl group, a vinyl group and amercapto group.

It is preferable in the second aspect of the present invention that theactive energy ray-curable compound comprised in the surface layermaterial comprises a compound having a moiety having silicone-basedand/or fluorine-containing substituent, and having at least one reactivegroup selected from the group consisting of a (meth)acryloyl group, avinyl group and a mercapto group.

It is preferable in the second aspect of the present invention that theactive energy rays are electron rays or ultraviolet rays.

It is preferable in the second aspect of the present invention that theactive energy rays are irradiated in an atmosphere having an oxygenconcentration of 500 ppm or less.

A third aspect of the present invention is an article with a compositehard coat layer comprising a hard coat layer on a surface of the articleand an anti-staining surface layer on a surface of the hard coat layer,wherein the article is obtained by applying a hard coat agentcomposition comprising an active energy ray-curable compound onto asurface of an article to be hard-coat-treated, thereby forming a hardcoat agent composition layer,

-   -   film-forming, on the surface of the hard coat agent composition        layer, with a surface layer material comprising an active energy        ray-curable compound having anti-staining property and/or        lubricating property, thereby forming a surface material layer,        and    -   irradiating active energy rays onto the formed hard coat agent        composition layer and surface material layer so as to cure the        two layers simultaneously, thereby forming a hard coat layer        contacting the surface of the article and an anti-staining        surface layer contacting the surface of the hard coat layer.

It is preferable in the present invention that the article is an opticalrecording medium, a magneto-optical recording medium, an optical lens,an optical filter, an anti-reflection film, or any one of variousdisplay elements. Examples of the display element include a liquidcrystal display, a CRT display, a plasma display and an EL display.

In the specification, the wording “a hard coat agent composition layer”means a hard coat layer which has not been cured or has been half-cured(i.e., has been partially cured). The wording “a surface material layer”means a surface layer, namely an anti-staining surface layer, which hasnot been cured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view which schematically illustrates an example ofthe layer structure of the article with a composite hard coat layer ofthe present invention.

FIG. 2 is a schematic sectional view of an example of the optical diskwith a composite hard coat layer of the present invention.

MODES FOR CARRYING OUT THE INVENTION

The following describes the embodiment of the present invention indetail with reference to FIG. 1.

FIG. 1 is a sectional view which schematically illustrates an example ofthe layer structure of the article with a composite hard coat layer ofthe present invention. In FIG. 1, a hard coat layer 2 is formed on asurface of an article 1 to be hard-coat-treated, and an anti-stainingsurface layer 3 is formed to contact the surface of the hard coat layer2. The combination of the hard coat layer 2 and the anti-stainingsurface layer 3 is referred to as the composite hard coat layer for thesake of convenience.

Examples of the article 1 include various objects for which hard coattreatment is necessary. Specific examples thereof include sheets orsubstrates made of a thermoplastic resin such as polyethyleneterephthalate (PET), polymethyl methacrylate, polyethylene,polypropylene and polycarbonate. However, the article 1 is not limitedto these examples. More specific examples of the article include anoptical recording medium, a magneto-optical recording medium, an opticallens, an optical filter, an anti-reflection film, and various displayelements such as a liquid crystal display, a CRT display, a plasmadisplay and an EL display.

First, a hard coat agent composition containing an active energyray-curable compound is applied onto a surface of the article 1 so as toform a hard coat agent composition layer. Next, a surface material layeris formed by film-forming with a surface layer material containing anactive energy ray-curable compound having anti-staining property and/orlubricating property on the surface of the hard coat agent compositionlayer. The following describes respective components of the hard coatagent composition and the surface layer material.

The active energy ray-curable compound contained in the hard coat agentcomposition is any compound having at least one active group selectedfrom a (meth)acryloyl group, a vinyl group and a mercapto group. Thestructure of this compound is not particularly limited. The activeenergy ray-curable compound preferably contains a polyfunctional monomeror oligomer containing, in the single molecule thereof, 2 or more,preferably 3 or more polymerizable groups in order to give a sufficienthardness to a hard coat.

Among such active energy ray polymerizable compounds, examples of thecompound having a (meth)acryloyl group include 1,6-hexanedioldi(meth)acrylate, triethylene glycol di(meth)acrylate, ethylene oxidemodified bisphenol A di(meth)acrylate, trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate,ditrimethylolpropane tetra(meth)acrylate, dipentaerythritolhexa(meth)acrylate, pentaerythritol tri(meth)acrylate,3-(meth)acryloyloxyglycerin mono(meth)acrylate, urethane acrylate, epoxyacrylate, and ester acrylate. However, the compound having a(meth)acryloyl group is not limited to these examples.

Examples of the compound having a vinyl group include ethylene glycoldivinyl ether, pentaerythritol divinyl ether, 1,6-hexanediol divinylether, trimethylolpropane divinyl ether, ethylene oxide modifiedhydroquinone divinyl ether, ethylene oxide modified bisphenol A divinylether, pentaerythritol trivinyl ether, dipentaerythritol hexavinylether, and ditrimethylolpropane polyvinyl ether. However, the compoundhaving a vinyl group is not limited to these examples.

Examples of the compound having a mercapto group include ethylene glycolbis(thioglycolate), ethylene glycol bis(3-mercaptopropionate),trimethylolpropane tris(thioglycolate), trimethylolpropanetris(3-mercaptopropionate), pentaerythritol tetrakis(mercaptoacetate),pentaerythritol tetrakis(thioglycolate), and pentaerythritoltetrakis(3-mercaptopropionate). However, the compound having a mercaptogroup is not limited to these examples.

The active energy ray-curable compounds contained in the hard coat agentcomposition may be used alone or in combination of two or more thereof.

The hard coat agent composition may contain a known photopolymerizationinitiator. The photopolymerization initiator is not particularlynecessary when electron rays are used as the active energy rays.However, when ultraviolet rays are used, the initiator is necessary.Examples of a radical photo initiator, among the photopolymerizationinitiators, include a DAROCURE 1173, an IRGACURE 651, an IRGACURE 184,and an IRGACURE 907 (all of which are products manufactured by CibaSpecialty Chemicals Inc.). The content by percentage of thephotopolymerization initiator is, for example, from about 0.5 to 5% byweight of the hard coat agent composition (as a solid content).

If necessary, the hard coat agent composition may contain an inorganicfiller in order to improve the abrasion resistance. Examples of theinorganic filter include silica, alumina, zirconia and titania. Theaverage particle size of the inorganic filler is preferably 100 nm orless, more preferably 50 nm or less in the case that transparency isparticularly necessary.

In order to enhance the strength and the abrasion resistance of thecured coat, the surface of the inorganic filler is preferably modifiedwith a compound having an active energy ray polymerizable group. Theinorganic filler which has an average particle size of 50 nm or less andis surface-modified with a compound having an active energy raypolymerizable group may be made of reactive silica particles describedin, for example, Japanese Laid-open Patent Publication Nos. 11-60235(1999), 9-100111 (1997) and 2001-187812. This filler is preferably usedin the present invention. The silica particles described in JapaneseLaid-open Patent Publication No. 11-60235 (1999) contain acation-reactive oxetanyl group as a reactive group, and the silicaparticles described in Japanese Laid-open Patent Publication No.9-100111 (1997) contain a radical-reactive (meth)acryloyl group as areactive group. The silica particles described in Japanese Laid-openPatent Publication No. 2001-187812 contain both of a radical-reactiveunsaturated double bond of a (meth)acryloyl group or the like, and acation-reactive group of an epoxy group or the like. The addition ofsuch an inorganic filler to the hard coat composition makes it possiblethat the abrasion resistance of the hard coat layer is made higher. Thecontent by percentage of the inorganic filler is, for example, fromabout 5 to 80% by weight of the hard coat agent composition (as a solidcontent). If the content of the inorganic filler is more than 80% byweight, the film strength of the hard coat layer tends to become weak.

If necessary, the hard coat agent composition may further contain anon-polymerizable diluting solvent, a photopolymerization co-initiator,an organic filler, a polymerization inhibitor, an antioxidant, anultraviolet ray absorber, a photo-stabilizer, an antifoamer, a levelingagent, a pigment, a silicon compound and others. Examples of thenon-polymerizable diluting solvent include isopropyl alcohol, n-butylalcohol, methyl ethyl ketone, methyl isobutyl ketone, isopropyl acetate,n-butyl acetate, ethylcellosolve, and toluene.

The surface layer material is any material of which the cured film hasanti-staining property and/or lubricating property. That is to say, thesurface layer material is not particularly limited, provided that itimparts anti-staining property (water repellency and/or oil repellency)and/or lubricity to the surface layer and it has an active energy raypolymerizable functional group. For example, the surface layer materialmay be a silicone compound or a fluorine-containing compound containingat least one active energy ray polymerizable functional group selectedfrom a (meth)acryloyl group, a vinyl group, and a mercapto group.Anti-staining property and/or lubricity is/are provided by thesilicone-based substituent or the fluorine-containing substituent.Generally, the compound having the fluorine-containing substituentprovides more excellent anti-staining property and/or lubricity, namelylarger contact angle of water on the hard coat surface, than thecompound having the silicone-based substituent. The silicone compoundsmay include compounds containing a moiety with a silicone-basedsubstituent and at least one reactive group selected from a(meth)acryloyl group, a vinyl group, and a mercapto group. Specificexamples include, but are not limited to, compounds as represented bythe following formulae (1) to (3):R—[Si(CH₃)₂O]_(n)—R  (1);R—[Si(CH₃)₂O]_(n)—Si(CH₃)₃  (2); and(CH₃)₃SiO—[Si(CH₃)₂O]_(n)—[Si(CH₃)(R)O]_(m)—Si(CH₃)₃  (3),wherein R is a substituent containing at least one reactive groupselected from a (meth)acryloyl group, a vinyl group, and a mercaptogroup, n and m represent the degree of polymerization, n is in the rangeof 5 to 1000, and m is in the range of 2 to 100.

Examples of the fluorine-containing compound include afluorine-containing (meth)acrylate compound. Specific examples of thefluorine-containing (meth)acrylate compound include fluorinatedacrylates such as 2,2,3,3,3-pentafluoropropyl (meth)acrylate,2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,2-trifluoroethyl(meth)acrylate, 1H,1H,5H-octafluoropentyl(meth)acrylate,3-(perfluoro-5-methylhexyl)-2-hydroxypropyl (meth)acrylate,2-(perfluorooctyl)ethyl acrylate, 3-perfluorooctyl-2-hydroxypropyl(meth)acrylate, 2-(perfluorodecyl)ethyl (meth)acrylate,2-(perfluoro-9-methyloctyl)ethyl (meth)acrylate,3-(perfluoro-7-methyloctyl)ethyl (meth)acrylate,2-(perfluoro-9-methyldecyl)ethyl (meth)acrylate, and1H,H,9H-hexadecafluorononyl(meth)acrylate. However, thefluorine-containing (meth)acrylate compound is not limited to theseexamples. For example, it is also preferable to use a polymer such asperfluoropolyether into which a (meth) acrylate group is introduced, anda fluorine-containing compound having a vinyl or mercapto group insteadof a (meth)acrylate group, or some other compound. More specificexamples thereof include diacrylate of a Fombrin Z DOL (analcohol-modified perfluoropolyether product manufactured by AusimontCo.), and ART3 and ART4 (products manufactured by Kyoeisha Chemical Co.,LTD.).

The active energy ray-curable compounds contained in the surface layermaterial may be used alone or in combination of two or more selectedfrom the above-mentioned silicone compounds and fluorine-containingcompounds. The active energy ray-curable compound contained in thesurface layer material is preferably electron ray-curable compound. Thesurface layer material may contain, as a part of the components thereof,the active energy ray-curable compound used in the above-mentioned hardcoat agent composition.

In the same manner for the hard coat agent composition, the surfacelayer material may contain a non-polymerizable diluting solvent, aphotopolymerization initiator, a photopolymerization co-initiator, anorganic filler, an inorganic filler, a polymerization inhibitor, anantioxidant, an ultraviolet ray absorber, a photo-stabilizer, anantifoamer, a leveling agent, a pigment, a silicon compound and othersif necessary.

In the present invention, the above-mentioned hard coat agentcomposition is first applied onto the surface of the article 1 to form ahard coat agent composition layer. The coating method for theapplication is not limited, and may be any one of various coatingmethods such as spin coating, dip coating and gravure coating methods.

After the hard coat agent composition is applied onto the surface of thearticle 1 and before the film is formed with the surface layer material,it is preferable to remove the fluidity of the hard coat agentcomposition layer. The removal of the fluidity of the hard coat agentcomposition layer makes it possible to prevent a variation in thethickness of the hard coat agent composition layer or a deterioration inthe surface flatness thereof when the film is formed with the surfacelayer material on this composition layer. In this way, the surface layermaterial can easily be made into a uniform film.

To remove the fluidity of the hard coat agent composition layer, forexample, in the case that a diluting solvent is contained in the hardcoat agent composition, it is advisable to dry, after the application ofthe composition, the applied layer so as to remove the solvent containedin the composition from the hard coat agent composition layer. It isalso allowable to irradiate, after the application and optional dryingof the applied layer, active energy rays such as ultraviolet rays ontothe layer so as to turn the hard coat agent composition layer into ahalf-cured state. Attention should be paid to the irradiation of theactive energy rays so as not to cure the hard coat agent compositionlayer completely. The word “half-cured” means that a part of the appliedhard coat agent composition has not yet reacted. Accordingly, thephysical hardness of the hard coat agent composition layer is notlimited. Thus, the tackiness of the surface is allowed to be lost. Theirradiation amount of the ultraviolet rays at this time, which dependson the thickness of the hard coat layer, is for example, from 1 to 500mJ/cm², preferably from 1 to 200 mJ/cm². The ultraviolet ray irradiationamount of such a degree makes it possible that the hard coat agentcomposition layer is easily made into a half-cured state.

The thickness of the hard coat layer obtained by curing the hard coatagent composition layer is not particularly limited, and may beappropriately decided in accordance with the kind or the use of thearticle. In the case that the article is, for example, an opticalrecording disk, it is advisable to set the thickness into 1 μm or moreand 10 μm or less, preferably 1 μm or more and 5 μm or less. If thethickness is less than 1 μm, a sufficient surface hardness cannot begiven to the disk. If the thickness exceeds 10 μm, the disk tends to becracked or largely warped.

Next, a surface material layer is formed by film-forming with theabove-mentioned surface layer material on the surface of the hard coatagent composition layer which has not been cured or which has beenpartially cured (i.e., which is in the half-cured state). It isadvisable to form the surface material layer in such a manner that thethickness of an anti-staining surface layer obtained after the surfacematerial layer is cured will be made into 1 nm or more and 100 nm orless, preferably 5 nm or more and 50 nm or less. If the thickness isless than 1 nm, effects of anti-staining property and lubricity are notsufficiently obtained. If the thickness exceeds 100 nm, the hardness ofthe underlying hard coat layer is not sufficiently reflected. Thus,effects of scratch resistance and abrasion resistance decrease.

The film-forming can be conducted by the application or the depositionof the surface layer material. The surface layer material is applied bydiluting the surface layer material with a suitable solvent and thenapplying the resultant coating solution by any one of various methodssuch as spin coating, dip coating, gravure coating, and spray coatingmethods. After the application, the resultant layer is dried.

It is preferred to use, as the solvent in this case, a solvent in whichthe active energy ray-curable compound in the hard coat agentcomposition layer which has not been cured or has been partially curedis not substantially dissolved. It depends on not only the kind of thesolvent but also the coating method whether or not the hard coat agentcomposition layer is substantially dissolved. In many cases in which asthe coating method of the surface material layer, for example, spincoating is used, almost all of the diluting solvent contained in thecoating solution volatilizes when the spin coating is performed.Therefore, even if a solvent in which the hard coat agent compositionlayer is dissolved to some degree is used as the diluting solvent, nopractical problems are caused. In the case that as the coating method ofthe surface material layer, for example, dip coating is used, the hardcoat agent composition layer surface which has not been cured contactsthe surface material layer coating solution for a long time. It istherefore necessary to use a solvent in which the hard coat agentcomposition layer material is not at all dissolved or is hardlydissolved.

Examples of the solvent which can be used in dip coating includesaturated hydrocarbons such as n-hexane, cyclohexane, n-octane andisooctane, silicon compounds such as hexamethyldisiloxane,octamethyltrisiloxane and octamethylcyclotetrasiloxane, andfluorocarbons such as perfluorohexane, perfluoroheptane andperfluorooctane. Examples of the solvent which can be used in spincoating include isopropyl alcohol, n-butyl alcohol, dibutyl ether,ethylcellosolve, butylcellosolve, methyl perfluorobutyl ether, ethylperfluorobutyl ether, HFC 43-10mee, and1,1,2,2,3,3,4-heptafluorocyclopentane besides the above-mentionedvarious solvents.

In this way, the hard coat agent composition layer which has not beencured or has been partially cured and the surface material layer whichis positioned on the surface thereof and has not been cured are formed.

Next, the formed hard coat agent composition layer and surface materiallayer are irradiated with active energy rays so as to be simultaneouslycured. At this time, the active energy rays having an energy amountsufficient to cure the two layers completely are irradiated to completethe curing reaction of the two layers. At this time, the irradiationamount of electron rays is, for example, from 1 to 50 Mrad, preferablyfrom 3 to 30 Mrad. The accelerating voltage of the electron rays is, forexample, from 20 to 200 kV. However, in an optical recording mediumcomprising recording layer described later, the accelerating voltage is,for example, from 20 to 100 kV, preferably from 30 to 70 kV so as not todamage the recording layer. By curing, at the same time, the hard coatagent composition layer which has not been cured or has been partiallycured and the surface material layer which is formed to contact thesurface thereof and has not been cured, the two layers are firmlyadhered to each other in the interface therebetween. That is, the curedanti-staining surface layer 3 adhered firmly onto the cured hard coatlayer 2 is obtained.

By use of such a process of the present invention, it is possible toform, on the high-hardness hard coat layer 2, the anti-staining surfacelayer 3 which is so thin as to reflect the hardness thereof on thetopmost surface and is good in water repellency and lubricity and,further, it is possible to obtain good adhesion between the hard coatlayer 2 and the anti-staining surface layer 3.

As the means for curing the hard coat agent composition layer and thesurface material layer simultaneously, suitable means selected fromactive energy rays such as ultraviolet rays, electron rays, and visiblerays may be used. However, in the present invention, to set thethickness of the anti-staining surface layer into a very small value,such as a value of 1 nm or more and 100 nm or less, preferably 5 nm ormore and 50 nm or less and obtain better adhesion of the surface layerto the hard coat layer, it is necessary to use the curing method capableof exhibiting the good reactivity near the interface of the both layer.

Specifically, if either electron rays or ultraviolet rays should be usedas the active energy rays, it is preferable to conduct purging withinert gas such as nitrogen in such a manner that the oxygenconcentration in the atmosphere for the active energy ray irradiationwill be 500 ppm or less, preferably 200 ppm or less and more preferably10 ppm or less. This is because the hindrance of the surface-curing,resulting from oxygen radicals generated in the irradiation atmosphere,is suppressed. Alternatively, known various oxygen-hindrance inhibitorsmay be added to the hard coat agent composition and/or the materialhaving anti-staining and lubricating property instead of the control ofthe oxygen concentration in the irradiation atmosphere. Examples of suchan oxygen-hindrance inhibitor include oxygen-hindrance inhibitorsdescribed in Japanese Laid-open Patent Publication Nos. 2000-109828,2000-109828 and 2000-144011. Needless to say, it is allowable to useboth of the oxygen-hindrance inhibitor and the control of the oxygenconcentration in the irradiation atmosphere.

By use of such materials and such film-forming and film-curing methods,there is formed a composite hard coat layer which is excellent inabrasion resistance, water repellency and lubricity and is also good inpersistence of these properties.

EXAMPLES

The present invention will be described more specifically by way of thefollowing examples. However, the present invention is not limited tothese examples.

Example 1

An ultraviolet ray-curable/electron ray-curable hard coat agent(DESOLITE Z7503, manufactured by JSR Corp.) was applied onto apolycarbonate substrate (thickness: 0.6 mm, diameter: 12 cm) by spincoating. Thereafter, the resultant was heated at 60° C. in theatmosphere for 3 minutes, to remove the diluting solvent in the coat. Inthis way, a hard coat layer which had not been cured was formed. Theabove-mentioned hard coat agent was a composition containing a reactiveinorganic filler, disclosed in Japanese Laid-open Patent Publication No.9-100111 (1997).

Next, a solution comprising 0.2% by mass of silicone acrylate(X-22-2445, manufactured by Shin-Etsu Chemical Co., Ltd.) which has thestructure represented by following formula (4), and 99.8% by mass ofn-octane was applied onto the above-mentioned hard coat layer which hadnot been cured by spin coating. The resultant was dried at 60° C. for 1minute to form a surface layer which had not been cured.R—[Si(CH₃)₂O]_(n)—R  (4)(R: —C₃H₆OCOCH═CH₂, Polymerization degree n: about 40)

Next, electron rays was irradiated onto the surface layer under nitrogenflow, thereby curing the hard coat layer and the surface layersimultaneously. A CURETRON (manufactured by NHV Corp.) was used as anelectron rays irradiating device, and the accelerating voltage of theelectron rays and the irradiation amount thereof were set to 200 kV and5 Mrad, respectively. The oxygen concentration in the irradiationatmosphere was 80 ppm. The thickness of the hard coat layer was 3.2 μm,and the thickness of the surface layer was about 21 nm. The thickness ofthe hard coat layer was measured with a stylus profilometer. Thethickness of the surface layer was measured by X-ray fluorescenceanalysis (XRF), using silicone oil (KF-96, manufactured by Shin-EtsuChemical Co., Ltd.) as a standard material. In this way, the substratewith the composite hard coat layer was obtained.

Example 2

An ultraviolet ray-curable/electron ray-curable hard coat agent(DESOLITE Z7503, manufactured by JSR Corp.) was applied onto apolycarbonate substrate (thickness: 0.6 mm, diameter: 12 cm) by spincoating. Thereafter, the resultant was heated at 60° C. in theatmosphere for 3 minutes, to remove the diluting solvent in the coat. Inthis way, a hard coat layer which had not been cured was formed.

Next, a solution comprising 0.2% by mass of 2-(perfluorodecyl)ethylacrylate (manufactured by Daikin Fine Chemical laboratory Co.) and 99.8%by mass of FLUORINERT FC-77 (manufactured by Sumitomo 3M Ltd.) wasapplied onto the above-mentioned hard coat layer which had not beencured by spin coating. The resultant was dried at 60° C. for 3 minutesto form a surface layer which had not been cured. Thereafter, under thesame electron ray irradiating condition as Example 1, electron rays wasirradiated onto the surface layer under nitrogen flow, thereby curingthe hard coat layer and the surface layer simultaneously. The thicknessof the hard coat layer was 3.1 μm, and the thickness of the surfacelayer was about 30 nm. The thickness of the surface layer was measuredby X-ray fluorescence analysis (XRF), using perfluoropolyether (DEMNUM,manufactured by Daikin Industries, Ltd.) as a standard material. In thisway, the substrate with the composite hard coat layer was obtained.

Example 3

An ultraviolet ray-curable/electron ray-curable hard coat agent(DESOLITE Z7503, manufactured by JSR Corp.) was applied onto apolycarbonate substrate (thickness: 0.6 mm, diameter: 12 cm) by spincoating. The resultant was heated at 60° C. in the atmosphere for 3minutes, to remove the diluting solvent in the coat. Thereafter,ultraviolet rays (a high-pressure mercury lamp, 100 mJ/cm²) wasirradiated in the atmosphere, a hard coat layer which had beenhalf-cured was formed.

Next, 0.2 parts by weight of silicone acrylate (X-22-2445, manufacturedby Shin-Etsu Chemical Co., Ltd.) and 0.04 parts by weight photo radicalinitiator (IRGACURE 907 manufactured by Ciba Specialty Chemicals Inc.)were added to 100 parts by weight of propylene glycol monomethyl ethersolvent. This solution was applied onto the above-mentioned hard coatlayer which had been half-cured by spin coating. The resultant was driedat 60° C. for 1 minute to form a surface layer which had not been cured.

Next, ultraviolet rays (a high-pressure mercury lamp, 2,000 mJ/cm²) wasirradiated onto the surface layer under nitrogen flow, thereby curingthe hard coat layer and the surface layer simultaneously. The oxygenconcentration in the ultraviolet ray radiation atmosphere was 5 ppm. Thethickness of the hard coat layer was 3.2 μm, and the thickness of thesurface layer was about 25 nm. The thickness of the surface layer wasmeasured by X-ray fluorescence analysis (XRF), using silicone oil(KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.) as a standardmaterial. In this way, the substrate with the composite hard coat layerwas obtained.

Comparative Example 1

5 parts by weight of 2-(perfluorooctyl)ethyl acrylate (manufactured byDaikin Fine Chemical laboratory Co.) was added, as a fluorinatedacrylate, to 95 parts by weight of ultraviolet ray-curable/electronray-curable hard coat agent (DESOLITE Z7503, manufactured by JSR Corp.)so as to prepare the uniform composition. This composition was appliedonto a polycarbonate substrate (thickness: 0.6 mm, diameter: 12 cm) byspin coating. Thereafter, electron rays was immediately irradiated undernitrogen flow, thereby the substrate with the composite hard coat layerwas obtained. Electron ray irradiating condition was the same asExample 1. The thickness of the hard coat layer was 3.0 μm.

Comparative Example 2

An ultraviolet ray-curable/electron ray-curable hard coat agent(DESOLITE Z7503, manufactured by JSR Corp.) was applied onto apolycarbonate substrate (thickness: 0.6 mm, diameter: 12 cm) by spincoating. The resultant was heated at 60° C. in the atmosphere for 3minutes, to remove the diluting solvent in the coat. Thereafter,ultraviolet rays (a high-pressure mercury lamp, 2,000 mJ/cm²) wasirradiated in the atmosphere, a hard coat layer which had beencompletely cured was formed.

Next, a solution comprising 0.2% by mass of silicone acrylate(X-22-2445, manufactured by Shin-Etsu Chemical Co., Ltd.) and 99.8% bymass of n-octane was applied onto the above-mentioned hard coat layerwhich had been completely cured by spin coating. The resultant was driedat 60° C. for 1 minute to form a surface layer which had not been cured.Thereafter, under the same electron ray irradiating condition as Example1, electron rays was irradiated onto the surface layer under nitrogenflow, thereby curing the surface layer. In this way, the substrate withthe composite hard coat layer was obtained. The thickness of the hardcoat layer was 3.3 μm, and the thickness of the surface layer was about16 nm.

(Evaluation)

About the respective specimens produced in Examples 1 to 3 andComparative Examples 1 and 2, the following performance tests were made.

(1) Abrasion Resistance

A steel wool #0000 was used, and the wool was reciprocated 20 times soas to be slid onto the hard coat surface of each of the specimens undera load of 4.9N/cm². The degree of injuries generated at this time wasjudged with the naked eye. The criterion for the judgment was asfollows:

-   ◯: No injuries were generated.-   Δ: Injuries were slightly generated.-   X: Injuries were generated.    (2) Water Repellency and Persistence Thereof

The contact angle of water to the hard coat layer surface of eachspecimen was measured. The measurement was made at initial time andafter the specimen surface was slid with a cloth impregnated with asolvent respectively. Conditions for the sliding were as follows: anonwoven cloth (Bemcot Lint-free CT-8, manufactured by Asahi Kasei Co.,Ltd.) was impregnated with acetone, and the cloth was reciprocated 50times to be slid on the specimen surface under a load of 4.9 N/cm². Thecontact angle was measured at a temperature of 20° C. and a relativehumidity of 60%, using a contact angle meter CA-D manufactured by KyowaInterface Science Co., Ltd. TABLE 1 Contact angle (degrees) SurfaceAbrasion After the layer resistance Initial sliding Example 1 Silicone ◯98.7 97.8 type Example 2 Fluorine ◯ 105.3 103.0 type Example 3 Silicone◯ 96.1 93.4 type Comparative Fluorine ◯ 67.0 65.7 Example 1 typeComparative Silicone ◯ 85.7 58.2 Example 2 type

The results are shown in Table 1.

As can be seen from Table 1, each of the substrates of Examples 1through 3 with respective hard coat layers had significantly highsurface hardness, high water repellency, and high durability.Specifically, since fluorinated acrylate was used to anti-stainingsurface layer, the substrates with hard coat layer of Example 2 had anexcellent performance.

Although the same material as in Example 2 was used in ComparativeExample 1, the substrate of Comparative Example 1 showed significantlylow water repellency at the initial time, as did it after the slidingwith cloth. Specifically, its intended purpose was not achieved becausethe fluorinated acrylate components were not exposed on the coatingsurface just by applying the fluorinated acrylate-added active energyray-curable resin onto the substrate and then curing it. Furthermore, inComparative Example 1, significant unevenness of coating was observedduring application of the prepared composition to the surface of thesubstrate. This is thought to occur since the diluent evaporates duringspin-coating, and the acryl monomer and the fluorinated acrylates, whichare incompatible to one another, rapidly underwent phase separation.This also makes the composition impractical for use in the hard coat.

Although the same material as in Example 1 was used in ComparativeExample 2, the substrate of Comparative Example 2 showed lower waterrepellency than that of Example 1 at the initial time, and significantlylow water repellency after the sliding with cloth. The reason why thesurface layer was applied and cured after having been completely cured.That is, the adhesion between the surface layer and the hard coat layerwas low.

Example 4

This example was a production example of an optical information mediumwith a composite hard coat layer (abbreviated to the optical disk). Inthis example, the produced optical disk was of a phase-change type. Thepresent invention can be applied to various disks regardless of the kindof their recording layer. Thus, the present invention can be applied tonot only this disk but also a read only type optical disk, a write oncetype optical disk or some other disk.

FIG. 2 is a schematic sectional view of an example of an optical diskwith a composite hard coat layer. In FIG. 2, an optical disk 11 has, ona surface of a supporting substrate 12 in which fine concavity orconvexity (such as information pits or pregrooves) are made, areflecting layer 13, a second dielectric layer 14, a phase-changerecording material layer 15, and a first dielectric layer 16 in thisorder. The disk 11 has a light-transmitting layer 18 on the firstdielectric layer 16, and further has a hard coat layer 19 and ananti-staining surface layer 20 on the light-transmitting layer 18. Inthis example, the reflecting layer 13, the second dielectric layer 14,the phase-change recording material layer 15 and the first dielectriclayer 16 constitute a recording layer 17. The combination of the hardcoat layer 19 and the anti-staining surface layer 20 is referred to asthe composite hard coat layer for the sake of convenience. The opticaldisk 11 is used in such a manner that a laser ray for recording orreproducing is radiated into the recording layer through theanti-staining surface layer 20, the hard coat layer 19 and thelight-transmitting layer 18.

A sample of the optical disk having the layer structure illustrated inFIG. 2 was produced as follows.

The reflecting layer 13 made of Al₉₈Pd₁Cu₁ (atomic ratio) and having athickness of 100 nm was formed on a surface of the disk-form supportingsubstrate 12 (made of polycarbonate, diameter: 120 mm, thickness: 1.1mm), in which grooves for recording information were made, bysputtering. The depth of the grooves was λ/6 in an optical path lengthat wavelength λ=405 nm. The recording track pitch in a groove recordingmanner was set into 0.32 μm.

Next, a Al₂O₃ target was used to form the second dielectric layer 14having a thickness of 20 nm on the surface of the reflecting layer 13 bysputtering. An alloy target made of a phase-change material was used toform the recording material layer 15 having a thickness of 12 nm on thesurface of the second dielectric layer 14 by sputtering. The composition(atomic ratio) of the recording material layer 15 was set intoSb₇₄Te₁₈(Ge₇In₁). A ZnS (80% by mole)-SiO₂ (20% by mole) target was usedto form the first dielectric layer 16 having a thickness of 130 nm onthe surface of the recording material layer 15 by sputtering.

Next, a radical-polymerizable ultraviolet ray-curable resin having thefollowing composition was applied onto the surface of the firstdielectric layer 16 by spin coating, and then ultraviolet rays wereirradiated thereon so as to form the light-transmitting layer 18 in sucha manner that the thickness thereof would be 98 μm after the layer 18was cured.

(Light-Transmitting Layer: Composition of Ultraviolet Ray-Curable Resin)urethane acrylate oligomer: 50 parts by weight (DIABEAM UK6035,manufactured by Mitsubishi Rayon Co., Ltd.) isocyanuric acid EO modifiedtriacrylate: 10 parts by weight (ARONIX M315, manufactured by ToagoseiCo., Ltd.) isocyanuric acid EO modified diacrylate:  5 parts by weight(ARONIX M215, manufactured by Toagosei Co., Ltd.) tetrahydrofurfurylacrylate: 25 parts by weight photopolymerizationinitiator(1-hydroxycyclohexyl  3 parts by weight phenyl ketone):

Next, an ultraviolet ray-curable/electron ray-curable hard coat agenthaving the following composition was applied onto the light-transmittinglayer 18 by spin coating, and then the resultant was heated at 60° C. inthe atmosphere for 3 minutes to remove the diluting solvent in the coat.In this way, the hard coat layer 19 which had not been cured was formed.

(Composition of Hard Coat Agent)

-   reactive group modified colloidal silica: 100 parts by weight

(dispersing medium: propylene glycol monomethyl ether acetate,nonvolatile content: 40% by weight) dipentaerythritol hexaacrylate: 48parts by weight tetrahydrofurfuryl acrylate: 12 parts by weightpropylene glycol monomethyl ether acetate: 40 parts by weight(non-reactive diluting solvent) IRGACURE 184 (polymerization initiator): 5 parts by weight

Next, a solution comprising 0.25% by mass of 2-(perfluorodecyl)ethylacrylate (manufactured by Daikin Fine Chemical laboratory Co.) and99.75% by mass of FLUORINERT FC-77 (manufactured by Sumitomo 3M Ltd.)was applied onto the above-mentioned hard coat layer 19 which had notbeen cured by spin coating. The resultant was dried at 60° C. for 3minutes to form the surface layer 20 which had not been cured.

Thereafter, electron rays was irradiated onto the surface layer undernitrogen flow, thereby curing the hard coat layer 19 and the surfacelayer 20 simultaneously. A Min-EB (manufactured by USHIO Inc.) was usedas an electron rays irradiating device, and the accelerating voltage ofthe electron rays and the irradiation amount thereof were set to 50 kVand 5 Mrad, respectively. The oxygen concentration in the irradiationatmosphere was 80 ppm. The thickness of the hard coat layer 19 was 2.5μm, and the thickness of the surface layer 20 was about 28 nm. Thethickness of the surface layer was measured by X-ray fluorescenceanalysis (XRF), using perfluoropolyether (DEMNUM, manufactured by DaikinIndustries, Ltd.) as a standard material. In this way, the opticalrecording disk sample No. 1 with the composite hard coat layer wasobtained.

Comparative Example 3

In the same way as in Example 4, a reflecting layer 13, a seconddielectric layer 14, a phase-change recording material layer 15, and alight-transmitting layer 18 were formed, in the oder, on a surface of adisk-form supporting substrate 12.

Next, an ultraviolet ray-curable/electron ray-curable hard coat agenthaving the following composition was applied onto the light-transmittinglayer 18 by spin coating. Thereafter, electron rays was immediatelyirradiated onto the layer 18 under nitrogen flow. In this way, theoptical recording disk sample No. 2 with the composite hard coat layerwas obtained. Electron ray irradiating condition was the same as inExample 4. The thickness of the hard coat layer was 2.8 μm.

(Composition of Hard Coat Agent)

-   reactive group modified colloidal silica: 100 parts by weight

(dispersing medium: propylene glycol monomethyl ether acetate,nonvolatile content: 40% by weight) dipentaerythritol hexaacrylate: 48parts by weight tetrahydrofurfuryl acrylate: 12 parts by weightpropylene glycol monomethyl ether acetate: 40 parts by weight(non-reactive diluting solvent) 2-(perfluorooctyl)ethyl acrylate  5parts by weight IRGACURE 184 (polymerization initiator):  5 parts byweight

Comparative Example 4

In the same way as in Example 4, a reflecting layer 13, a seconddielectric layer 14, a phase-change recording material layer 15, and alight-transmitting layer 18 were formed, in the oder, on a surface of adisk-form supporting substrate 12.

Next, an ultraviolet ray-curable/electron ray-curable hard coat agenthaving the same composition as used in Example 4 was applied onto thelight-transmitting layer 18 by spin coating, and then the resultant washeated at 60° C. in the atmosphere for 3 minutes to remove the dilutingsolvent in the coat. Thereafter, ultraviolet rays (a high-pressuremercury lamp, 2,000 mJ/cm²) was irradiated onto the layer 18 in theatmosphere, the hard coat layer which had been completely cured wasformed.

Next, a solution comprising 0.25% by mass of silicone acrylate(X-22-2445, manufactured by Shin-Etsu Chemical Co., Ltd.) and 99.75% bymass of n-octane was applied onto the above-mentioned hard coat layerwhich had been completely cured by spin coating. The resultant was driedat 60° C. for 1 minute to form a surface layer which had not been cured.Thereafter, under the same electron ray irradiating condition as Example4, electron rays was irradiated onto the surface layer under nitrogenflow, thereby curing the surface layer. In this way, the opticalrecording disk sample No. 3 with the composite hard coat layer wasobtained. The thickness of the hard coat layer was 3.0 μm, and thethickness of the surface layer was about 21 nm.

(Evaluation)

About the respective optical recording disk samples Nos. 0.1 to 3produced in Example 4 and Comparative Examples 3 and 4, an optical diskevaluating device (DDU-1,000, manufactured by Pulstec Industrial Co.,Ltd.) was used to evaluate the recording/reproducing property under thefollowing conditions:

-   -   laser wavelength: 405 nm;    -   objective lens numerical aperture NA: 0.85;    -   linear velocity: 6.5 m/s;    -   recording signals: 1-7 modulating signals (shortest signal        length: 2 T); and    -   recording area: groove recording.        (1) Abrasion Resistance

Random signals were recorded at a position about 40 mm apart in theradius direction from the center of the respective optical recordingdisk samples. The initial jitter values thereof were then measured.Next, a steel wool #0000 was reciprocated 20 times so as to be slid onthe hard coat side surface of the respective disks under a load of 2.5N/cm². Thereafter, the jitter values (jitter value after the test) wereagain measured. The direction in which the steel wool was slid was madeinto the radius direction of the disk, and the used steel wool had asize of 1.0 cm×1.0 cm.

(2) Anti-Staining Property

Random signals were recorded at a position about 40 mm apart in theradius direction from the center of the respective optical recordingdisk samples. The initial jitter values thereof were then measured.Next, a middle finger was pushed against a position of the hard coatside surface of the respective disks about 40 mm apart in the radiusdirection from the center of the respective disks at a pushing force of9.8 N for 10 seconds. In the way, the fingerprint was adhered thereon.Thereafter, 8 pieces from a commercially available facial tissue(manufactured by Crecia Corp.), which were in layers, were used to wipeoff the disk slowly from the inner circumference thereof to the outercircumference so as to remove the fingerprint. The pushing force at thetime of the wiping off was set into 4.9 N/cm², and the number of thewiping operation(s) was set into one. Thereafter, the jitter values(jitter value after the test) were again measured. TABLE 2 Jitter value(%) After the Initial test Optical Abrasion 7.6 7.6 recording diskresistance sample No. 1 Anti-staining 7.6 7.8 property Optical Abrasion13.5 16.2 recording disk resistance sample No. 2 Anti-staining 13.5 17.3property Optical Abrasion 7.7 7.8 recording disk resistance sample No. 3Anti-staining 7.7 13.5 property

Results of the above-mentioned measurements are shown in Table 2.

As is clear from Table 2, the optical recording disk sample No. 1 wasexcellent in the initial jitter value and the jitter value after theboth of the abrasion resistance test and anti-staining test.

In the above-mentioned example, the composite hard coat layer was givento the phase-change type optical disks. However, the present inventioncan be applied to read only type optical disks or write once typeoptical disks as well as optical disks having a phase-change typerecording layer. The present invention can also be applied to not onlyoptical information media but also optical lens, optical filters,anti-reflection films, and various display elements. Therefore, theabove-mentioned working examples are merely examples in all points, andthe present invention should not be restrictedly interpreted by theexamples. Furthermore, all modifications belonging to a scope equivalentto that of the claims are within the scope of the present invention.

INDUSTRIAL APPLICABILITY

According to the present invention, an article with a hard coat, whichhas high abrasion resistance, good water repellency and lubricity, andsignificantly high durability, is inexpensively and easily provided.

1. An article comprising a hard coat layer on the surface of the articleand an anti-staining surface layer on the surface of the hard coatlayer, wherein the hard coat layer comprises a cured product of a hardcoat agent composition comprising an active energy ray-curable compound,the anti-staining surface layer comprises a cured product of a surfacelayer material comprising an active energy ray-curable compound havinganti-staining property and/or lubricating property, and theanti-staining surface layer is fixed on the hard coat layer.
 2. Thearticle according to claim 1, wherein the anti-staining surface layerhas a thickness of 1 nm or more and 100 nm or less.
 3. The articleaccording to claim 1, wherein the active energy ray-curable compoundcomprised in the hard coat agent composition is a compound having atleast one reactive group selected from the group consisting of a(meth)acryloyl group, a vinyl group and a mercapto group.
 4. The articleaccording to claim 1, wherein the active energy ray-curable compoundcomprised in the surface layer material is a compound having at leastone reactive group selected from the group consisting of a(meth)acryloyl group, a vinyl group and a mercapto group.
 5. The articleaccording to claim 1, wherein the active energy ray-curable compoundcomprised in the surface layer material comprises a compound having amoiety having silicone-based and/or fluorine-containing substituent, andhaving at least one reactive group selected from the group consisting ofa (meth)acryloyl group, a vinyl group and a mercapto group.
 6. Thearticle with the composite hard coat layer according to claim 1, whereinthe hard coat agent composition comprises a photopolymerizationinitiator, and optionally an inorganic filler.
 7. A method for forming acomposite hard coat layer comprising a hard coat layer and ananti-staining surface layer on a surface of an article, which comprisesapplying a hard coat agent composition comprising an active energyray-curable compound onto the surface of the article, thereby forming ahard coat agent composition layer, film-forming, on the surface of thehard coat agent composition layer, with a surface layer materialcomprising an active energy ray-curable compound having anti-stainingproperty and/or lubricating property, thereby forming a surface materiallayer, and irradiating active energy rays onto the formed hard coatagent composition layer and surface material layer so as to cure the twolayers simultaneously, thereby forming a hard coat layer contacting thesurface of the article and an anti-staining surface layer contacting thesurface of the hard coat layer.
 8. The method for forming the compositehard coat layer according to claim 7, wherein the thickness of theanti-staining surface layer is 1 nm or more and 100 nm or less.
 9. Themethod for forming the composite hard coat layer according to claim 7,further comprising drying the hard coat agent composition layer toremove a solvent contained in the hard coat agent composition from thehard coat agent composition layer after said applying the hard coatagent composition step, and before said film-forming step.
 10. Themethod for forming the composite hard coat layer according to claim 7,further comprising optionally drying the hard coat agent compositionlayer, and irradiating active energy rays onto the hard coat agentcomposition layer to turn the composition layer into a half-cured stateafter said applying the hard coat agent composition step, and beforesaid film-forming step.
 11. The method for forming the composite hardcoat layer according to claim 7, wherein said film-forming is carriedout by applying or depositing.
 12. The method for forming the compositehard coat layer according to claim 11, wherein said film-forming iscarried out by dissolving the surface layer material in a solventwherein the active energy ray-curable compound in the already-formedhard coat agent composition layer is not substantially dissolved, andapplying the surface layer material.
 13. The method for forming thecomposite hard coat layer according to claim 7, wherein the activeenergy ray-curable compound comprised in the hard coat agent compositionis a compound having at least one reactive group selected from the groupconsisting of a (meth)acryloyl group, a vinyl group and a mercaptogroup.
 14. The method for forming the composite hard coat layeraccording to claim 7, wherein the active energy ray-curable compoundcomprised in the surface layer material is a compound having at leastone reactive group selected from the group consisting of a(meth)acryloyl group, a vinyl group and a mercapto group.
 15. The methodfor forming the composite hard coat layer according to claim 7, whereinthe active energy ray-curable compound comprised in the surface layermaterial comprises a compound having a moiety having silicone-basedand/or fluorine-containing substituent, and having at least one reactivegroup selected from the group consisting of a (meth)acryloyl group, avinyl group and a mercapto group.
 16. The method for forming thecomposite hard coat layer according to claim 7, wherein the activeenergy rays are electron rays or ultraviolet rays.
 17. The method forforming the composite hard coat layer according to claim 7, wherein saidirradiating step is carried out in an atmosphere having an oxygenconcentration of 500 ppm or less.
 18. An article comprising a hard coatlayer on a surface of the article and an anti-staining surface layer ona surface of the hard coat layer, wherein the article is produced byapplying a hard coat agent composition comprising an active energyray-curable compound onto the surface of the article, thereby forming ahard coat agent composition layer, film-forming, on the surface of thehard coat agent composition layer, with a surface layer materialcomprising an active energy ray-curable compound having anti-stainingproperty and/or lubricating property, thereby forming a surface materiallayer, and irradiating active energy rays onto the formed hard coatagent composition layer and surface material layer to cure the twolayers simultaneously, thereby forming a hard coat layer contacting thesurface of the article and an anti-staining surface layer contacting thesurface of the hard coat layer.
 19. The article with a composite hardcoat layer according to claim 1, wherein the article is an opticalrecording medium, a magneto-optical recording medium, an optical lens,an optical filter, an anti-reflection film, or a display element. 20.The article with a composite hard coat layer according to claim 18,wherein the article is an optical recording medium, a magneto-opticalrecording medium, an optical lens, an optical filter, an anti-reflectionfilm, or a display element.